LGV Coupling and Uncoupling

Question 1

What is the first thing a driver should check before coupling a tractor unit to a semi-trailer?

Accepted Answer

That the trailer is on a firm, level surface with the parking brake applied and the landing gear supports it

Answer

That the radio is turned off

Answer

That the trailer doors are open

Answer

That the trailer is fully loaded

Question 2

After the 5th wheel has engaged with the trailer kingpin, what test must the driver perform?

Accepted Answer

A pull test (tug test) — gently try to pull away with the trailer brakes applied to confirm the coupling is locked

Answer

A speed test

Answer

A fuel economy test

Answer

A horn test

Question 3

In what order should the air lines (susies) be connected when coupling?

Accepted Answer

It does not matter which order

Answer

Connect the emergency (red) line first, then the service (yellow) line

Answer

Connect the service (yellow) line first, then the emergency (red) line

Answer

Only one line needs connecting

Question 4

What should a driver visually check on the 5th wheel after coupling?

Accepted Answer

That the locking jaws are closed around the kingpin, the release handle is in the locked position, and there are no gaps

Answer

Only that the trailer is straight

Answer

That the 5th wheel is painted

Answer

Only the 5th wheel grease

Question 5

When must the trailer landing gear (legs) be fully raised after coupling?

Accepted Answer

After confirming the coupling is secure and before driving away

Answer

They can stay down during driving

Answer

Only when loading the trailer

Answer

Landing gear is only used for uncoupling

Question 6

What is the purpose of the trailer service line (yellow coupling)?

Accepted Answer

To supply air pressure that operates the trailer service brakes when the driver presses the brake pedal

Answer

To supply emergency air to the trailer

Answer

To supply electricity to the trailer

Answer

To provide air for the trailer tyres